Interstitial Brachytherapy With or Without External-Beam Radiation Therapy in Treating Patients With Prostate Cancer

OBJECTIVES:

- Compare the 5-year freedom from progression in patients with intermediate-risk prostate
cancer treated with interstitial brachytherapy with or without external beam
radiotherapy (EBRT).

- Compare biochemical (i.e., prostate-specific antigen) failure, biochemical failure by
the Phoenix definition, disease-specific survival, local progression, and distant
metastases in patients treated with these regimens.

- Compare morbidity and quality of life of patients treated with these regimens.

- Determine the feasibility of collecting Medicare data in a large RTOG prostate cancer
clinical trial for cost effectiveness and cost utility analysis of combined treatment
with interstitial brachytherapy and EBRT.

- Prospectively collect diagnostic biopsy samples from these patients for future
biomarker analyses.

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to
disease stage (T1c vs T2a or T2b), Gleason score (≤ 6 vs 7), prostate-specific antigen (< 10
ng/mL vs 10-20 ng/mL), and prior neoadjuvant hormonal therapy (yes vs no). Patients are
randomized to 1 of 2 treatment arms.

- Arm I: Patients undergo external beam radiotherapy 5 days a week for 5 weeks. Within
2-4 weeks of radiotherapy, patients undergo interstitial brachytherapy with iodine I
125 or palladium Pd 103 seeds.

- Arm II: Patients undergo interstitial brachytherapy only, as in arm I. Quality of life
is assessed at baseline, at 4, 12, and 24 months, and then annually for 3 years.

After completion of study treatment, patients are followed at 3-5 weeks, at 4, 6, 9, and 12
months, every 6 months for 4 years, and then annually thereafter.

DISEASE CHARACTERISTICS:

- Histologically confirmed adenocarcinoma of the prostate

- T1c-T2b, N0, M0

- Intermediate-risk disease, as defined by 1 of the following:

- Gleason score < 7 AND prostate-specific antigen (PSA) 10-20 ng/mL

- Gleason score 7 AND PSA < 10 ng/mL

- No evidence of distant metastases

- Prostate volume ≤ 60 cc by transrectal ultrasonography

- American Urological Association voiding symptom score no greater than 15 (alpha
blockers allowed)

PATIENT CHARACTERISTICS:

Age

- 18 and over

Performance status

- Zubrod 0-1

Life expectancy

- Not specified

Hematopoietic

- Not specified

Hepatic

- Not specified

Renal

- Not specified

Other

- Patients must use effective contraception

- No other malignancy within the past 5 years except basal cell or squamous cell skin
cancer or carcinoma in situ at any other site

- No major medical or psychiatric illness that would preclude study therapy

- No hip prosthesis

PRIOR CONCURRENT THERAPY:

Biologic therapy

- Not specified

Chemotherapy

- No prior chemotherapy

Endocrine therapy

- Prior neoadjuvant hormonal therapy allowed provided the following are true:

- Therapy was initiated within 2-6 months of study enrollment

- Therapy was no more than 6 months in duration

- Use of 5-alpha reductase inhibitors (e.g., finasteride) is discontinued before
registration

- No concurrent hormonal therapy

Radiotherapy

- No prior pelvic radiotherapy

Surgery

- No prior radical surgery for prostate cancer

- No prior transurethral resection of the prostate

- No prior cryosurgery

Other

- No prior transurethral needle ablation of the prostate

- No prior transurethral microwave thermotherapy of the prostate